Spark Core Blinking Blue

I have been trying to connect my Spark Core to my WiFi router but no success. I have factory reset the core, so LED started blinking Blue. WHen I tried to configure it using Android App, it couldn’t find core and core also kept blinking Blue. I also tried using USB but same issue.
Can someone guide me, how to connect this core to Cloud?

Have you had a look here already?

Especially check if your router settings comply.

OK, I was able to now send WiFI credentials, but it doesn’t go furher bu blinks Green. Any clue?

It is a new core that has never connected successfully to the :cloud:?